Startlingly Rapid Greenland Ice Sheet Melt Begs Question: Why?

— July 26, 2012

Scientists will grapple ‘for years’ to best understand the whys and wherefores of a four-day rapid melting affecting 97 percent of Greenland’s enormous ice sheet. ‘Weird’ in a number of ways … but precise role of global warming remains to be determined.

That startlingly rapid four-day widespread melt of Greenland’s massive ice sheet between July 8 and July 12?

It was “global weirding” for sure. And “weird weather” by any stretch. Just what it has to do with global warming remains to be best answered by the relevant scientists, whose reasoned assessments we’ll have to eagerly await.

But don’t worry. They’re on it.

The before-and-after images of Greenland’s ice sheet instantly attracted widespread media attention, and deservedly so given the speed and scope of the melt. Which is not to suggest that it was necessarily unprecedented or even unforeseen.

Image courtesy of NASA/JPL.

Much of the initial media coverage reflected the cautionary approach taken by NASA’s Jet Propulsion Laboratory in announcing the melt. The best reports on the melt noted that such events have occurred previously, most recently in 1889. But they noted too that this melt event is the first noted in the observational record now at the start of its 90th decade.

Some others, however, rushed to mistakenly headline the event as if the entire ice sheet had melted — WRONG. Oy Vey.

(Had the whole ice sheet melted away over just four days, some have observed, we hardly would have had to wait long to learn about it in headlines, no matter how 24/7 they might be.)

So what gives? AP’s Borenstein, The New York Times’ Kelly Slivka, and others noted that such melting is not unprecedented … only highly unusual. Both reported the JPL points that the ice melt area had increased from about 40 percent of the ice sheet to about 97 percent in just four days. (The most extensive seen by satellites over the past 30 years was about 55 percent, Borenstein reported.)

Both Borenstein and Slivka picked up too on another point made by NASA/JPL:

Summer in Greenland has been freakishly warm so far. That’s because of frequent high pressure systems that have parked over the island, bringing warm clear weather that melts ice and snow, explained University of Georgia climatologist Thomas Mote.

Every 150 Years over the past 10,000

Slivka reported NASA Goddard Space Flight Center glaciologist Lora Koenig as saying the July 8-12 melt, while an extreme event, needs to be seen in a historical context: over the past 10,000 years of its history, large-scale melting events have occurred roughly every 150 years or so. With the previous huge melt in 1889, this latest extreme melt appears to be running pretty much on schedule.

Koenig pointed out too that surface ice on the sheet’s summit appeared to be within one degree Celsius — about 1.8 degrees Fahrenheit — of refreezing, which may have gotten under way around the July 14 end of the melt.

In his syndicated report, AP’s Borenstein quoted NASA chief scientist Waleed Abdalati as saying “It’s a big signal, the meaning of which we’re going to sort out for years to come.”

No More ‘Steady-State’ Arctic Climate

While “dramatic and worrisome to many climate scientists,” Freedman reported, the sudden melt “does not necessarily mean that Greenland is headed for a far faster and more significant melt than scientists already anticipate.” He reported on an e-mail exchange with University of Colorado research associate William Colgan: “Since we are looking at a record event, rather than a trend,” Colgan had written to him, “it is not really possible to directly translate this into a projection of future ice sheet behavior.”

Freedman also reported Colgan’s comment that “Perhaps all we can say is that the frequency with which Greenland melt years are being established is exceptional. It clearly demonstrates that the Arctic climate is no longer in steady-state … but rather that Arctic climate is in a highly transient state, whereby progressively more extreme events are exceeded as climate trends in a given direction.”

“I think it is clear that entire ice sheet melt events are now increasing in frequency as a result of anthropogenic [manmade] climate change, rather than natural variability in solar isolation,” Colgan wrote.

Freedman concluded that this particular melt “was set off by unusually mild weather conditions that have occurred more frequently in that region during recent summers.” He pointed to NASA/JPL’s finding of a number of upper-atmosphere high pressure centers, or “ridges,” over Greenland since May, leading to mild air temperatures and reduced cloud coverage … “similar to the weather patterns that have caused record heat in much of the U.S. this summer.”

“Is it weird weather? And not only in Greenland in mid-July but across much of North America throughout the spring and now well into the sultry and drought-stricken summer months?”

The null hypothesis would presume that it’s natural variability and not weird weather, but that’s objective science, which is dull and boring when compared to the subjectivity of emotions. The human condition is what assumes and then assigns the “weird” adjective. And the human condition is biased inherently towards “the moment” (or dare I say “extreme”) when it comes to weather and even climate.

What’s more interesting with this event is that the mainstream media outlets reported it with startling uniformity. However, the same routinely neglects to report cold weather events with such a common voice (e.g., the past, several years of very cold European winters).

There was a time (not too long ago) when humanity accepted the weather as a reliably unpredictable entity. Today, though, humanity has the bizarre notion that not only can the weather be “reliably” predicted (vis-a-vis a “forecast,” of course) but so, too, can the climate. We seemingly have the IPCC (and others) to thank for the rapid adoption of a decidedly destructive form of hubris.